MongoTemplate aggregation operation MongoDB

... Aggregation is simply to provide data statistics, analysis, and classification methods. This is similar to mapreduce, except that mongodb does more encapsulation and optimization, making data operations more convenient and Easy to use. The Aggregation operation receives the data set of...


DB - postgresql installation and simple use

... install sudo apt-get install postgresql This command creates a linux user named postgres by default, no password. Equivalent to the root user without password in mysql. default client operation Login client: sudo -u postgres psql Create user: create user 'username' with password ...


ThinkPHP5.0.20+PHP+AJAX classification paging loading function.

... This project issued by the company this month, need to be an information exchange website, where the mobile phone loading is using the waterfall first time thought It's a plugin, but I still want to write it myself, I don't want to rely on plugins. The requirement is like this: you need...


EntityFramework dynamic multi-condition query and Lambda expression tree + page query

... initial use linq to sql is not familiar with the query statement, hereby record Query page method (transfer) /// < Summary> /// paged query + conditional query + sort /// </summary> /// <typeparam name="Tkey">generic</typeparam> /// <param name="pageSize">...


Illustrate MySQL inner join, outer join, left join, right join, full join

... with two tables (a_table, b_table), associated fields a_table.a_id and b_table.b_id to demonstrate MySQL inner join, outer join ( Left (outside) connection, right (outside) connection, full (outside) connection). MySQL version: Server version: 5.6.31 MySQL Community Server (GPL)...


Hierarchical domain model specification

... DO (Data Object): This object has a one-to-one correspondence with the database table structure, and the data source object is transmitted upward through the DAO layer. DTO (Data Transfer Object): Data transfer object, Service or Manager external transfer object BO (Business Object):...


Mysql binlog_format mode and configuration details

... mysql replication There are three main ways: based on SQL statement-based replication (SBR), Row-based replication (RBR), mixed-based replication (MBR). Correspondingly, there are three formats for binlog: STATEMENT, ROW, MIXED. 1 STATEMENT mode (SBR) Each sql statement that will modify...


Ali and Weibo's off-site multi-living program

... : 多活基础线线 : Each center is alive and can bear the traffic in real time. Any problem can be cut off directly, and it can be directly taken over by another point. The non-traditional two-site three-center cold standby method. 挑战和解决方法 : Service delay. Let the operations all be done in the...


Spring boot project mvn package command will detect database connection

... project structure sprignboot + maven + mysql + docker when the project is packaged mvn clean package error: com.alibaba.druid.pool.DruidDataSource: create connection error, url: jdbc:mysql://10.77.0.2:3306/cms?characterEncoding=utf8&useSSL=true, errorCode 0, state 08S01 view the...


Single-machine MySQL database optimization recommended compiler installation parameters

... MySQL Compilation parameters are many and complex, so that novices feel very big, if the official build environment to install MySQL, there is not enough time to study the meaning of each parameter, personal advice Using the compilation parameters compiled by Yu Hongchun's predecessors,...